The invention relates to a do-it-yourself spiral staircase with a central column made of a hollow steel tube, which extends between the base support on a lower floor and a landing plate or end tread on an upper floor of a dwelling or office building.
Spiral staircases are known, wherein the central columns are made of an integral steel tube, with a screw nut welded into its head portion. In order to secure the central column to the landing plate or to the upper tread on the upper floor, a clamping bolt engages the nut. At the footing end of the central column is welded a stand or bottom plate which rests on the lower support on the lower floor and is fixedly anchored to the lower floor by bolts or dowels. On the central column are aligned, one above the other, the individual treads, spaced from each other by spacer sleeves. By pre-stressing the central column at the head thereof with respect to the landing plate or the upper tread, the several treads with the spacer sleeves therebetween are simultaneously firmly pressed to each other.